ALBERT

Description: Hubble Space Telescope imaging observations of two nearby brown dwarfs, DENIS-P J1228.2-1547 and Kelu 1, made with the near-infrared camera and multiobject spectrometer (NICMOS), show that the DENIS object is resolved into two components of nearly equal brightness with a projected separation of 0.275 arc second (5 astronomical units for a distance of 18 parsecs). This binary system will be able to provide the first dynamical measurement of the masses of two brown dwarfs in only a few years. Upper limits to the mass of any unseen companion in Kelu 1 yield a planet of 7 Jupiter masses aged 0. 5 x 10(9) years, which would have been detected at a separation larger than about 4 astronomical units. This example demonstrates that giant planets could be detected by direct imaging if they exist in Jupiter-like orbits around nearby young brown dwarfs.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Martin -- Brandner -- Basri -- New York, N.Y. -- Science. 1999 Mar 12;283(5408):1718-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy, University of California, Berkeley, CA 94720, USA. Jet Propulsion Laboratory/Infrared Processing and Analysis Center, Mail Code 100-22, Pasadena, CA 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10073933" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Basri, Gibor -- New York, N.Y. -- Science. 2006 Feb 3;311(5761):618-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Astronomy Department, University of California at Berkeley, Berkeley, CA 94720, USA. basri@berkeley.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16456068" target="_blank"〉PubMed〈/a〉

Description: The Kepler mission was designed to determine the frequency of Earth-sized planets in and near the habitable zone of Sun-like stars. The habitable zone is the region where planetary temperatures are suitable for water to exist on a planet's surface. During the first 6 weeks of observations, Kepler monitored 156,000 stars, and five new exoplanets with sizes between 0.37 and 1.6 Jupiter radii and orbital periods from 3.2 to 4.9 days were discovered. The density of the Neptune-sized Kepler-4b is similar to that of Neptune and GJ 436b, even though the irradiation level is 800,000 times higher. Kepler-7b is one of the lowest-density planets (approximately 0.17 gram per cubic centimeter) yet detected. Kepler-5b, -6b, and -8b confirm the existence of planets with densities lower than those predicted for gas giant planets.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Borucki, William J -- Koch, David -- Basri, Gibor -- Batalha, Natalie -- Brown, Timothy -- Caldwell, Douglas -- Caldwell, John -- Christensen-Dalsgaard, Jorgen -- Cochran, William D -- DeVore, Edna -- Dunham, Edward W -- Dupree, Andrea K -- Gautier, Thomas N 3rd -- Geary, John C -- Gilliland, Ronald -- Gould, Alan -- Howell, Steve B -- Jenkins, Jon M -- Kondo, Yoji -- Latham, David W -- Marcy, Geoffrey W -- Meibom, Soren -- Kjeldsen, Hans -- Lissauer, Jack J -- Monet, David G -- Morrison, David -- Sasselov, Dimitar -- Tarter, Jill -- Boss, Alan -- Brownlee, Don -- Owen, Toby -- Buzasi, Derek -- Charbonneau, David -- Doyle, Laurance -- Fortney, Jonathan -- Ford, Eric B -- Holman, Matthew J -- Seager, Sara -- Steffen, Jason H -- Welsh, William F -- Rowe, Jason -- Anderson, Howard -- Buchhave, Lars -- Ciardi, David -- Walkowicz, Lucianne -- Sherry, William -- Horch, Elliott -- Isaacson, Howard -- Everett, Mark E -- Fischer, Debra -- Torres, Guillermo -- Johnson, John Asher -- Endl, Michael -- MacQueen, Phillip -- Bryson, Stephen T -- Dotson, Jessie -- Haas, Michael -- Kolodziejczak, Jeffrey -- Van Cleve, Jeffrey -- Chandrasekaran, Hema -- Twicken, Joseph D -- Quintana, Elisa V -- Clarke, Bruce D -- Allen, Christopher -- Li, Jie -- Wu, Haley -- Tenenbaum, Peter -- Verner, Ekaterina -- Bruhweiler, Frederick -- Barnes, Jason -- Prsa, Andrej -- New York, N.Y. -- Science. 2010 Feb 19;327(5968):977-80. doi: 10.1126/science.1185402. Epub 2010 Jan 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉NASA Ames Research Center, Moffett Field, CA 94035, USA. William.J.Borucki@nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20056856" target="_blank"〉PubMed〈/a〉

Description: Surface gravity is a basic stellar property, but it is difficult to measure accurately, with typical uncertainties of 25 to 50 per cent if measured spectroscopically and 90 to 150 per cent if measured photometrically. Asteroseismology measures gravity with an uncertainty of about 2 per cent but is restricted to relatively small samples of bright stars, most of which are giants. The availability of high-precision measurements of brightness variations for more than 150,000 stars provides an opportunity to investigate whether the variations can be used to determine surface gravities. The Fourier power of granulation on a star's surface correlates physically with surface gravity: if brightness variations on timescales of hours arise from granulation, then such variations should correlate with surface gravity. Here we report an analysis of archival data that reveals an observational correlation between surface gravity and root mean squared brightness variations on timescales of less than eight hours for stars with temperatures of 4,500 to 6,750 kelvin, log surface gravities of 2.5 to 4.5 (cgs units) and overall brightness variations of less than three parts per thousand. A straightforward observation of optical brightness variations therefore allows a determination of the surface gravity with a precision of better than 25 per cent for inactive Sun-like stars at main-sequence to giant stages of evolution.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bastien, Fabienne A -- Stassun, Keivan G -- Basri, Gibor -- Pepper, Joshua -- England -- Nature. 2013 Aug 22;500(7463):427-30. doi: 10.1038/nature12419.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy, Vanderbilt University, 1807 Station B, Nashville, Tennessee 37235, USA. fabienne.a.bastien@vanderbilt.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23969460" target="_blank"〉PubMed〈/a〉

Description: Ten days of photometric data were obtained during the commissioning phase of the Kepler mission, including data for the previously known giant transiting exoplanet HAT-P-7b. The data for HAT-P-7b show a smooth rise and fall of light from the planet as it orbits its star, punctuated by a drop of 130 +/- 11 parts per million in flux when the planet passes behind its star. We interpret this as the phase variation of the dayside thermal emission plus reflected light from the planet as it orbits its star and is occulted. The depth of the occultation is similar in photometric precision to the detection of a transiting Earth-size planet for which the mission was designed.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Borucki, W J -- Koch, D -- Jenkins, J -- Sasselov, D -- Gilliland, R -- Batalha, N -- Latham, D W -- Caldwell, D -- Basri, G -- Brown, T -- Christensen-Dalsgaard, J -- Cochran, W D -- DeVore, E -- Dunham, E -- Dupree, A K -- Gautier, T -- Geary, J -- Gould, A -- Howell, S -- Kjeldsen, H -- Lissauer, J -- Marcy, G -- Meibom, S -- Morrison, D -- Tarter, J -- New York, N.Y. -- Science. 2009 Aug 7;325(5941):709. doi: 10.1126/science.1178312.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉NASA Ames Research Center, Moffett Field, CA 94035, USA. william.j.borucki@nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19661420" target="_blank"〉PubMed〈/a〉

Description: The Kepler spacecraft is monitoring more than 150,000 stars for evidence of planets transiting those stars. We report the detection of two Saturn-size planets that transit the same Sun-like star, based on 7 months of Kepler observations. Their 19.2- and 38.9-day periods are presently increasing and decreasing at respective average rates of 4 and 39 minutes per orbit; in addition, the transit times of the inner body display an alternating variation of smaller amplitude. These signatures are characteristic of gravitational interaction of two planets near a 2:1 orbital resonance. Six radial-velocity observations show that these two planets are the most massive objects orbiting close to the star and substantially improve the estimates of their masses. After removing the signal of the two confirmed giant planets, we identified an additional transiting super-Earth-size planet candidate with a period of 1.6 days.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Holman, Matthew J -- Fabrycky, Daniel C -- Ragozzine, Darin -- Ford, Eric B -- Steffen, Jason H -- Welsh, William F -- Lissauer, Jack J -- Latham, David W -- Marcy, Geoffrey W -- Walkowicz, Lucianne M -- Batalha, Natalie M -- Jenkins, Jon M -- Rowe, Jason F -- Cochran, William D -- Fressin, Francois -- Torres, Guillermo -- Buchhave, Lars A -- Sasselov, Dimitar D -- Borucki, William J -- Koch, David G -- Basri, Gibor -- Brown, Timothy M -- Caldwell, Douglas A -- Charbonneau, David -- Dunham, Edward W -- Gautier, Thomas N 3rd -- Geary, John C -- Gilliland, Ronald L -- Haas, Michael R -- Howell, Steve B -- Ciardi, David R -- Endl, Michael -- Fischer, Debra -- Furesz, Gabor -- Hartman, Joel D -- Isaacson, Howard -- Johnson, John A -- MacQueen, Phillip J -- Moorhead, Althea V -- Morehead, Robert C -- Orosz, Jerome A -- New York, N.Y. -- Science. 2010 Oct 1;330(6000):51-4. doi: 10.1126/science.1195778. Epub 2010 Aug 26.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA. mholman@cfa.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20798283" target="_blank"〉PubMed〈/a〉

Description: Aurorae are detected from all the magnetized planets in our Solar System, including Earth. They are powered by magnetospheric current systems that lead to the precipitation of energetic electrons into the high-latitude regions of the upper atmosphere. In the case of the gas-giant planets, these aurorae include highly polarized radio emission at kilohertz and megahertz frequencies produced by the precipitating electrons, as well as continuum and line emission in the infrared, optical, ultraviolet and X-ray parts of the spectrum, associated with the collisional excitation and heating of the hydrogen-dominated atmosphere. Here we report simultaneous radio and optical spectroscopic observations of an object at the end of the stellar main sequence, located right at the boundary between stars and brown dwarfs, from which we have detected radio and optical auroral emissions both powered by magnetospheric currents. Whereas the magnetic activity of stars like our Sun is powered by processes that occur in their lower atmospheres, these aurorae are powered by processes originating much further out in the magnetosphere of the dwarf star that couple energy into the lower atmosphere. The dissipated power is at least four orders of magnitude larger than what is produced in the Jovian magnetosphere, revealing aurorae to be a potentially ubiquitous signature of large-scale magnetospheres that can scale to luminosities far greater than those observed in our Solar System. These magnetospheric current systems may also play a part in powering some of the weather phenomena reported on brown dwarfs.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hallinan, G -- Littlefair, S P -- Cotter, G -- Bourke, S -- Harding, L K -- Pineda, J S -- Butler, R P -- Golden, A -- Basri, G -- Doyle, J G -- Kao, M M -- Berdyugina, S V -- Kuznetsov, A -- Rupen, M P -- Antonova, A -- England -- Nature. 2015 Jul 30;523(7562):568-71. doi: 10.1038/nature14619.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA. ; Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK. ; Department of Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK. ; Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109-0899, USA. ; Centre for Astronomy, National University of Ireland, Galway, University Road, Galway, Republic of Ireland. ; Department of Mathematical Sciences, Yeshiva University, New York, New York 10033, USA. ; Astronomy Department, University of California, Campbell Hall, Berkeley, California 94720, USA. ; Armagh Observatory, College Hill, Armagh BT61 9DG, UK. ; Kiepenheuer Institut fur Sonnenphysik, Schoneckstrasse 6, D-79104 Freiburg, Germany. ; Institute of Solar-Terrestrial Physics, Irkutsk 664033, Russia. ; National Radio Astronomy Observatory, PO Box O, Socorro, New Mexico 87801, USA. ; Department of Astronomy, Faculty of Physics, St Kliment Ohridski University of Sofia, 5 James Bourchier Boulevard, 1164 Sofia, Bulgaria.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26223623" target="_blank"〉PubMed〈/a〉

Description: We report rotation periods, variability characteristics, gyrochronological ages for ~950 of the Kepler Object of Interest host stars. We find a wide dispersion in the amplitude of the photometric variability as a function of rotation, likely indicating differences in the spot distribution among stars. We use these rotation periods in combination with published spectroscopic measurements of v sin i and stellar parameters to derive the stellar inclination in the line of sight, and find a number of systems with possible spin–orbit misalignment. We additionally find several systems with close-in planet candidates whose stellar rotation periods are equal to or twice the planetary orbital period, indicative of possible tidal interactions between these planets and their parent stars. If these systems survive validation to become confirmed planets, they will provide important clues to the evolutionary history of these systems.